Anti-fuses are commonly used in the semiconductor industry for one-time programming purposes. For example, anti-fuses can be used for updating and repairing in product configurations, such as repairing dynamic random access memory (DRAM) arrays by swapping defective cells with redundant cells.
Anti-fuse structures include a material which initially has a relatively high resistance, but after programming by electrical or optical means (e.g., when a voltage across the anti-fuse structure exceeds a certain level), is converted to a lower resistance material. In order to convert to the lower resistance material, known anti-fuses typically require voltages in excess of an on-chip power supply voltage to break down an insulating region between two conductors. As operating voltages continue to be scaled down, achieving and controlling sufficient anti-fuse programming voltage has become increasingly difficult. Precise electrical and physical control are also required to achieve reliable activation of anti-fuses.
Low processing cost and relatively high chip density are requirements as semiconductor technology continues to be scaled down. However, conventional methods for fabricating and activating known anti-fuses have become increasingly costly and an unattractive option.